Genesis 23:7-20 - The field and the cave were deeded to Abraham

23:7-16

Abraham asks for a particular tomb, but also insists on paying for it. Ephron, who owned the field and the cave which would be used for burial, wants to give the tomb to Abraham. In the end Abraham pays four hundred shekels of silver for the land. The whole process may be something of a pantomime, just a way of reaching a price in such a way that everyone is happy with the outcome and no one is embarrassed. All cultures have various pantomimes that must be gone through in order to do things “properly”.

23:17-20

The emphasis is that this land was rightfully given over to Abraham “as a possession in the presence of the Hittites”. I.e. it was given over legally and properly. Even today a common accusation against Israel is that they do not have a right to the land of Israel. So Sarah was buried in the land.